Microscale Fiber Network Structure Affects the Simulated Macroscale Failure of Collagen Gel Tissue Analogs

The microstructure of a soft tissue plays a significant role in shaping its failure properties at much larger length scales. However, delineating the specific relationship between microstructure and failure response has proven enigmatic. Important recent work has included the efforts of Quinn et al. to assess experimentally microscale collagen fiber realignment precipitated by mechanical damage in the facet capsular ligament [1] and of Ritter et al. to model the failure of extracellular matrices using a zipper network model [2]. In the present study, we employ a multiscale finite-element damage model to explore the impact of microscale fiber network morphology on the macroscale failure properties of a collagen gel tissue analog. To simulate damage, the model links the failure of discrete collagen fibers in networks at the microscale to the overall macroscale stress-strain response of the tissue analog. The model has the advantages of being able to accommodate a wide range of microstructural network morphologies and to simulate complex macroscale tissue geometries. By furthering our ability to link tissue microstructure to failure, we can improve methods for assessing injury in native soft tissues, enhance treatments for injured tissues, and engineer more resilient replacement tissues.